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21
UK
15 Terms and abbreviations
Cat�
Category
Category
Classification of the safety-related
parts of a controller as regards their
resistance to failures�
CCF
Common Cause Failure
DC
Diagnostic Coverage
MTTF
D
Mean Time To Dangerous
Failure
PFH
(PFH
D
)
Probability of (dangerous)
Failure per Hour
PL
Performance Level
PL to EN ISO 13849-1
SIL
Safety Integrity Level
SIL 1-4 to IEC 61508
PLC
Programmable Logic Controller
T
M
Mission Time
= maximum service life